西昆仑库喀阿孜Pb-Zn多金属矿床硫化物微量元素对矿床成因的制约OA

The Kukaazi Pb-Zn polymetallic deposit is located in Xihexiu township,Yecheng county,Xinjiang.The mining area comprises eastern,southern,and northern ore sections.The ore bodies occur predominantly as lenticular and vein-type formations hosted between the Mesoproterozoic Changcheng system marble,garnet-rich skarn,marble,and metamorphic tuff,exhibiting strata-bound characteristics.The genetic type of this deposit re-mains inadequately constrained.Therefore,this study endeavors to conduct in situ micro-area trace element anal-ysis of pyrite and pyrrhotite from the mining area using laser ablation inductively coupled plasma mass spec-trometry(LA-ICP-MS).The trace element signatures of these minerals will subsequently be utilized to constrain the genesis of the deposit.The results demonstrate that pyrite is characterized by enrichment in Ni(mean 43.7×10-6)and Se(mean 49.1×10-6),depletion in Co(mean 0.71×10-6),and extremely low Co/Ni ratios(0.01-0.02).Cu and Sn contents are consistently<1 ppm,collectively indicating a low-temperature sedimentary origin.Pyrrhotite exhibits significantly elevated Co and Ni contents compared to pyrite(mean values:188 ppm and 205 ppm,respectively).The Co/Ni ratios range between 0.02-0.67 and 1.58-1.74,suggesting multiple mineraliza-tion events.Furthermore,trace element occurrence modes reveal that in pyrite,Co,Ni,Mn,and Se exist primari-ly through isomorphic substitution of Fe or S atoms in the crystal lattice,while Pb and Bi occur as nanoscale par-ticles(typically<100 nm).In pyrrhotite,however,Pb and Bi manifest as micron-sized inclusions(1-10 μm).Based on integrated evidence from previous studies,Sb/Bi ratios,and regional Caledonian magmatism(460-450 Ma),the deposit is interpreted as having an initial submarine hydrothermal-sedimentary origin,overprinted by Ordovician magmatic-hydrothermal modification.This research establishes key geochemical constraints on multi-stage mineralization events in the West Kunlun Orogen.